Mice feel their pain just as intensely as larger, more expensive pets. Secondly, a good vet can cure a lot of mouse problems, and a consultation need not cost a fortune; phone around to get quotes. It is worth asking the receptionist whether the vet sees many mice, or asking the vet how they feel about treating mice.
Some vets will not be keen on treating certain animals if they have little experience of the species, whilst others will see it as a challenge. Whatever the problem, if the first vet you see says that nothing can be done, you can always get a second opinion at another surgery.
A different vet might see the problem in a different light. A second consultation could put your mind at rest. Dealing with suffering does not have to involve veterinary care, however; if you do not feel able to treat the mouse yourself and do not want to undertake a course of veterinary treatment, then it should be humanely euthanized.
Just don’t let the mouse suffer and hope that the problem will solve itself – that could count as neglect.
Please remember that the author is not a veterinary professional, and that this document cannot be a substitute for veterinary advice or consultation.